Display element and method of manufacturing display element

ABSTRACT

A display element includes a light emitting unit that supplies light; and an angle converting unit including a reflection surface, an output surface, and a flat surface. The angle converting unit converts an angle of the light by reflecting the light toward the output surface. The light emitting unit is arranged in a matrix in two directions substantially perpendicular each other on a standard plane. An inequality 0≦t&lt;p(p−d−f)(tan θa)/(p+d−f) is satisfied, where t is a distance between the flat surface and the output surface, p is a pitch of the light emitting unit arranged in a predetermined direction, d is a length of the light emitting unit, f is a length of the flat surface, and θa is an angle between the reflection surface and the standard plane.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present document incorporates by reference the entire contents ofJapanese priority documents, 2004-135940 filed in Japan on Apr. 30, 2004and 2004-147680 filed in Japan on May 18, 2004.

BACKGROUND OF THE INVENTION

1) Field of the Invention

The present invention relates to a display element and a method ofmanufacturing the display element, and more particularly, to an organicelectroluminescence (EL) element and a method of manufacturing the ELelement.

2) Description of the Related Art

An organic EL display using organic EL elements is currently in use. Theorganic EL display has a substrate made of a transparent material on anemission side and on a side opposite to the emission side of thedisplay. Since each layer that constitutes the organic EL element isextremely thin, the substrate is provided to fix and reinforce eachlayer. Light from a light emitting unit in the organic EL element istransmitted through the substrate on the emission side of the organic ELdisplay and emitted to the outside of the display. A portion of thelight from the light emitting unit sometimes experiences a totalreflection from a boundary of the substrate on the emission side andabsorbed in the inside of the organic EL display. To avoid this, varioustechnologies have been proposed to change an angle of the light from thelight emitting unit in the organic EL display in such a manner that thelight enters an output surface of the substrate at an angle equal to orsmaller than a critical angle are proposed as described in, for example,Japanese Patent Application Laid-Open No. 100189251, Japanese PatentApplication Laid-Open No. 2001-332388, and Japanese Patent ApplicationLaid-Open No. 2000-323272.

The technology disclosed in Japanese Patent Application Laid-Open No.10-189251 and the technology disclosed in Japanese Patent ApplicationLaid-Open No. 2001-332388 involve providing a reflection surface thatreflects the light from the light emitting unit to change the angle ofthe light. It is very difficult to provide a structure having only areflection surface without providing a substrate or the like on theemission side of the light emitting unit. Therefore, it is conceivableto provide the reflection surface on the emission side substrate at aposition corresponding to a periphery of the light emitting unit. In theconfiguration in which the reflection surface is provided on thesubstrate at a position corresponding to a periphery of the lightemitting unit, a portion of the light from the light emitting unittotally reflects from the output surface of the substrate and enters thereflection surface provided in a periphery of a light emitting unit inanother pixel. The light that enters the reflection surface of anotherpixel is considered to reflect from the reflection surface and anelectrode in the light emitting unit and allowed to emit from the outputsurface of the substrate.

However, when light supplied from a light emitting unit of one pixelenters a reflection surface provided corresponding to another pixel,so-called a crosstalk in which light of a different pixel is emitted mayoccur. The crosstalk may lead to deteriorations of image quality such asblurring of the contour of an image and recognition of a ghost imagethat cannot be displayed. The technology disclosed in Japanese PatentApplication Laid-Open No. 2003-323272 involves providing a diffuser onthe emission side of the substrate. Even when a diffuser is provided,crosstalk may occur similarly to the technologies described in JapanesePatent Application Laid-Open No. 10-189251 and Japanese PatentApplication Laid-Open No. 2001-332388. As a result, it is necessary toprevent the deterioration of image quality in displays including organicEL displays from occurring in order to emit light from the lightemitting unit efficiently.

The organic EL display may have a reduced contrast due to illuminationin the room or outside light such as solar radiation. In the case oforganic EL displays with a reflection electrode in the light emittingunit, the outside light that enters the light emitting unit from theobserver side reflects from the reflection electrode, so that theoutside light together with display light travels to the observer side,thereby causing a reduction in contrast. To reduce such a reduction incontrast, a technology involving using a low reflection electrode madeof a low reflective material in the light emitting unit of the organicEL display is conceived. Provision of a low reflective electrode in thelight emitting unit leads to a reduction in reflection toward theobserver side of the outside light that enters the light emitting unitto minimize a reduction in contrast.

The technology disclosed in Japanese Patent Application Laid-Open No.10-189251 involves providing a reflection surface in the periphery ofthe light emitting unit. To change the angle of light from the lightemitting unit and minimizing the reduction in contrast simultaneously,it may be considered sufficient to provide a reflection surface in theperiphery of the light emitting unit and a low reflection electrode inthe light emitting unit. However, when the reflection surface isprovided in the periphery of the light emitting unit, the outside lightthat enters the reflection surface may be reflected directly in thedirection of the observer side. The outside light that travels from thereflection surface in the direction of the observer without entering thelow reflection electrode may be considered to be a cause of a reductionin contrast. The outside light may travel in the direction of theobserver side after being reflected between the reflection surfaces aswell as traveling as it is in the direction of the observer side afterentering the reflection surface. Thus, when a reflection surface and alow reflection electrode are provided parallelly, the outside light maybe returned in the direction of the observer without entering the lowreflection electrode.

The present invention has been made in light of the problems and it isan object of the present invention to provide a display capable ofminimizing a reduction in image quality in emitting light from the lightemitting unit and a method of manufacturing the display.

SUMMARY OF THE INVENTION

To solve the above problems, and to achieve the goal, a display elementaccording to one aspect of the present invention includes a lightemitting unit that is provided on a standard plane, and supplies light;and an angle converting unit including a reflection surface that isprovided on a periphery of the light emitting unit, and reflects thelight from the light emitting unit, an output surface that outputs thelight from the light emitting unit and the reflection surface, and aflat surface that is provided between the reflection surfaces inparallel with the output surface. The angle converting unit converts anangle of the light by reflecting the light incident on the reflectionsurface from the light emitting unit toward the output surface. Thelight emitting unit is arranged in a matrix in two directionssubstantially perpendicular each other on the standard plane. Ageometrical shape of the angle converting unit satisfies followinginequality0≦t<p(p−d−f)(tan θa)/(p+d−f)  (1)where t is a distance between the flat surface and the output surface, pis a pitch at which the light emitting unit is arranged in apredetermined direction, d is a length of the light emitting unit in thepredetermined direction, f is a length of the flat surface in thepredetermined direction, and θa is an angle between the reflectionsurface and the standard plane.

The angle converting unit of the display element has reflection surfacesthat reflect the light from the light emitting units to change the angleof the light with respect to the standard plane. The light that reflectsfrom the reflection surfaces is converted to light having an angle withrespect to the standard plane smaller than the critical angle on theoutput surface. The light that reflects from the reflection surfaces andtravels toward the output surface totally reflects from the outputsurface and emitted to the outside. The light that is generated in thelight emitting unit and is not incident to the reflection surfacestravels as it is toward the output surface of the angle converting unit.When the distance between the reflection surfaces and the output surfaceis large, the light from the light emitting unit which light travelsobliquely toward the output surface without being incident to thereflection surfaces may sometimes be incident to the output surface atan angle equal to or greater than the critical angle. The light thattotally reflects from the output surface does not return toward thelight generating layer and travels in the direction toward other pixels.To reduce the occurrence of blurring of images or appearance of ghostimages, the light that travels toward the other pixels must be reduced.

The display element that is configured to satisfy the inequality (1)above can emit the light from the light emitting unit within the regionof adjacent two pixels even when the light form the light emitting unitof a pixel totally reflects from the reflection surfaces.

According to the present invention, the geometrical shape of the angleconverting unit preferably satisfies following inequality0≦t<p(p−d−f)(tan θa)/2(p+d−f).  (2)

The display element configured to satisfy the inequality (2) aboveallows the light from the light generating portion in a region of onepixel that is adjacent in a predetermined direction to the pixel inwhich the light has been generated even when the light totally reflectsfrom the emission surfaces. By limiting the occurrence of the crosstalkin the display element in a region of up to one pixel, a display elementthat can reduce the deterioration of image quality can be obtained.

According to the present invention, the reflection surface has alongitudinal direction in at least one of the two directionssubstantially perpendicular each other on the standard plane. With thedisplay element with reflection surfaces in at least one of the twodirections, the occurrence of the crosstalk can be limited to apredetermined range to reduce the deterioration of image quality.

A method according to another aspect of the present invention, which isfor manufacturing a display element that includes a light emitting unitthat is provided on a standard plane, and supplies light; and an angleconverting unit including a reflection surface that is provided on aperiphery of the light emitting unit, and reflects the light from thelight emitting unit, an output surface that outputs the light from thelight emitting unit and the reflection surface, and a flat surface thatis provided between the reflection surfaces in parallel with the outputsurface, includes bonding temporarily a holding substrate to a surfaceof a parallel plate; forming the reflection surface at a predetermineddistance from a surface on which the holding substrate is temporarilybonded by pressing a mold having the predetermined pattern to othersurface of the parallel plate opposite to the surface on which theholding substrate is temporarily bonded; bonding the surface of theparallel plate on which the reflection surface is formed and a substrateon which the light emitting unit is arranged in advance; and peeling theholding substrate temporarily bonded from the parallel plate.

With the display element of which the distance between the position ofthe extremity of each reflection surface on the side of the emissionsurface and the emission surface is adjusted, the light from the lightgenerating portions is prevented from being emitted at a position moreremote by a region of two pixels from the pixel in which the light hasbeen generated. The crosstalk occurs in the display element increasinglywhen the distance between the reflecting surfaces and the emissionsurface increases. Accordingly, it is necessary to produce a displayelement having a relatively small distance between the reflectionsurfaces and the emission surface to obtain a display element withreduced occurrence of crosstalk. The method of producing a displayelement according to one aspect of the present invention includestransferring a pattern to a parallel plate to which a holding substrateis temporarily bonded. By using the holding substrate, the breakage ofthe parallel plate can be prevented even when the pattern is transferredto a thin parallel plate. The pattern transfer onto a thin parallelplate enables one to easily produce display elements having a shortdistance between the reflection surfaces and the emission surface. Bytransferring a pattern to a thin parallel plate, a display elementhaving a short distance between the reflection surfaces and the emissionsurface can be produced with ease. The breakage of the holding substratecan be prevented by temporarily bonding the holding substrate with anadhesive that is peelable by irradiation of ultraviolet rays, or byheating or with water. This reduces the breakage of the parallel plateduring the production process and enables production of a displayelement with a reduced possibility of the occurrence of crosstalk.

A display element according to still another aspect of the presentinvention includes a light emitting unit that is provided on a standardplane, and supplies light; and an angle converting unit that includes areflection surface provided on a periphery of the light emitting unit,and converts an angle of the light by reflecting the light incident onthe reflection surface from the light emitting unit toward an outputsurface. A geometrical shape of the angle converting unit satisfiesfollowing inequality{a sin(1/n)}/2+π/4<θb<π/2  (3)where θb is an angle in radian between the reflecting surface and thestandard plane, and n is refractive index of a material of which theangle converting unit is made.

With the display element having an angle at which the reflectionsurfaces are provided with respect to the standard plane which anglesatisfies the inequality (3), the external light that enters theemission surface can travel to the light generating portion or otherreflection surface without reflecting the external light to the emissionside. The amount of the component of the light that reflects from thereflection surfaces and travels to the light generating portion, whichcomponent travels to the emission side, can be reduced by, for example,providing a low reflection electrode in each light generating portion.Some of the light that travels from a reflection surface to anotherreflection surface may travel to the emission side. The light thattravels to the emission side again after reflecting from the reflectionsurfaces twice totally reflects from the emission surface of the anglechanging portion to travel toward the light generating portion. Theamount of the light that travels toward the light generating portionafter reflecting twice from the reflecting surfaces totally reflectsfrom the emission surface can be reduced by reflecting again from thereflection surface or the like.

Accordingly, the display element can prevent the external light that isincident to the reflection surface from the emission side from beingemitted toward the side of the observer after being reflected from thereflection surface once or twice. The amount of the external light thatreflects from the reflection surfaces three times or more can be reducedby repeating the reflection. The amount of the external light that isincident to the light generating portion from the emission side and thentravels toward the emission side can be reduced by providing the lowreflection electrode. When a polarizing plate is provided on theemission side of the angle changing portion, the light, in particularthat reflects twice from the reflecting surfaces cannot in some cases beblocked with the polarizing plate due to a change in phase. According tothe present invention, the amount of the light that reflects twice fromthe reflecting surfaces and then travels toward the emission side can bereduced. Accordingly, a display element that can reduce thedeterioration of image quality when the light from the light generatingportions is emitted efficiently can be obtained.

According to the present invention, the light emitting unit is arrangedin a matrix in two directions substantially perpendicular each other onthe standard plane, and the reflection surface has a longitudinaldirection in at least one of the two directions. With the displayelement configured to include reflection surfaces in one of the twodirections that cross at substantially right angles to each other, thedeterioration of image quality can be reduced when the light from thelight generating portions is emitted efficiently.

According to the present invention, the light emitting unit is arrangedin a matrix in two directions substantially perpendicular each other onthe standard plane, and the angle converting unit includes a firstreflection surface having a longitudinal direction in a first directionfrom among the two directions; and a second reflection surface having alongitudinal direction in a second direction from among the twodirections. By providing the reflection surfaces that are oblong in thefirst direction and the reflecting surfaces that are oblong in thesecond direction, the amount of the external light can be reduced notonly by reflections between the opposing reflection surfaces but also byreflections between the adjacent reflection surfaces. This can furtherreduce the deterioration of contrast.

According to the present invention, the light emitting unit includes alow reflection portion at which a reflectivity of light incident to thelight emitting unit from the output surface is equal to or less than apredetermined value. By providing the low reflection portion in thelight generating portion, travel of the external light that is incidentto the light generating portion toward the observer can be minimized.This can reduce the deterioration of contrast.

The display element according to the present invention further includesa polarizing plate that transmits only a polarized light in a specificoscillation direction on the output surface of the angle convertingunit. When the polarizing plate is provided on the emission side of theangle changing portion, only the polarized light from the externallight, which polarized light vibrates in the specific oscillationdirection, is incident to the display element. For example, when a phaseplate is provided on the side of the light generating portion of thepolarizing plate, the oscillation direction of the polarized lightincident to the display element is changed with the phase plate. Thepolarized light, the oscillation direction of which is changed with thephase plate from the specific oscillation direction to an oscillationdirection different from the specific oscillation direction does nottransmit through the polarizing plate and is blocked. By providing thepolarizing plate, the travel of the external light toward the observercan be minimized. This can reduce the deterioration of contrast.

According to the present invention, a structure formed with the firstreflection surface and a structure formed with the second reflectionsurface have substantially same height in a direction normal to thestandard plane. The reflection surfaces are configured to have inclinedsurfaces that widen from the light generating portion to the emissionside. The reflection surfaces provided on a display element and thereflection surfaces provided on a display element adjacent thereto abuton a position on the emission side to form a structure. On the positionsof the structures on the emission side are formed edges. When the heightof the structure that are oblong in the first direction is differentfrom the height of the structure that are oblong in the seconddirection, the external light that reflects from the edge of a structurereflects from the edge of another structure that is adjacent to theformer structure before the external light is emitted through theemission surface. The light that reflects twice from the reflectionsurfaces may sometimes transmit through the polarizing plate due to achange in phase. By making the height of the structure that is oblong inthe first direction and the height of the structure that is oblong inthe second direction substantially the same, the light that reflectsfrom the edge of a structure can be prevented from reflecting from thereflection surfaces of another structure adjacent to the formerstructure. Since the reflection occurs only at the edge, a change inphase is small, the light that reflects from the edge is blocked withthe polarizing plate. In this manner, the emission of the external lightthat reflects from the edge of the structure toward the observer can beminimized. This can reduce the deterioration of contrast.

According to the present invention, the angle converting unit furtherincludes a light absorbing portion that absorbs light at a position onthe reflection surface on a side of the output surface. The reflectionsurfaces provided in a display element and the reflection surfacesprovided in a display element that is adjacent to the display elementabut on a position or extremity on the side of the emission surface toform edges. By providing the light absorbing portion at the position ofthe edges, the reflection of the external light that is incident to theedges can be prevented from reflecting from the edges. Prevention ofreflection of the external light that is incident to the edges reducesthe amount of the external light that travels toward the observer andreduces the deterioration of contrast. With the light absorbing portionprovided on the edges at which the reflecting surfaces abut, theabsorption of the display light by the light absorbing portion can beminimized. Accordingly, the display element that can absorb only theexternal light efficiently can be realized with minimizing thedeterioration of contrast.

The other objects, features, and advantages of the present invention arespecifically set forth in or will become apparent from the followingdetailed description of the invention when read in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of a main part of the display device with adisplay element according to a first embodiment of the presentinvention;

FIG. 2 is a cross-section of the main part of the display device shownin FIG. 1;

FIG. 3 is a schematic for explaining a crosstalk;

FIG. 4 is a schematic of an example of a layout of pixels and prismstructures;

FIG. 5A is a schematic of a production method of manufacturing a displayelement according to a second embodiment of the present invention;

FIG. 5B is a schematic of a production method of manufacturing a displayelement according to the second embodiment of the present invention;

FIG. 6 is a perspective view of a main part of a display device with adisplay element according to a third embodiment of the presentinvention;

FIG. 7 is a plan view of a main part of the display device shown in FIG.6;

FIG. 8 is a cross-section of a main part of the display device shown inFIG. 6;

FIG. 9 is a schematic for explaining how external light that enters thedisplay device shown in FIG. 6 travels;

FIG. 10 is a schematic for explaining how light reflects betweenadjacent reflection surfaces;

FIG. 11 is a schematic of the display element according to a variationof the third embodiment of the present invention;

FIG. 12 is a cross-section of a main part of a display device with adisplay element according to a fourth embodiment of the presentinvention;

FIG. 13 is a cross-section of a main part of a display device with adisplay element according to a fifth embodiment of the presentinvention;

FIG. 14 is a schematic for explaining how light reflects from an edge ofa prism structure; and

FIG. 15 is a schematic for explaining how light reflects from an edge ofa prism structure.

DETAILED DESCRIPTION

Exemplary embodiments of the present invention are explained in detailwith reference to the accompanying drawings.

FIG. 1 is a schematic perspective view of a main part of a displaydevice 100 with a display element according to a first embodiment of thepresent invention. The display device 100 is an organic EL display thatincludes organic EL elements, which are display elements according tothe first embodiment of the present invention. The display device 100includes an angle converting unit 110 laminated on a substrate 112. Thesubstrate 112 is an organic EL panel that has a plurality of lightemitting units 120. The light emitting units 120 are provided on astandard plane SS that is parallel to a main surface of the substrate112 in the form of a matrix that extends in X and Y directions, whichare substantially at right angles to each other.

The angle converting unit 110 includes a parallel plate made of atransparent resin material. The angle converting unit 110 includes prismstructures 102 and 104 on a surface thereof on the side of the substrate112. Each of the prism structures 102 and 104 has reflection surfacesprovided in the periphery of each light emitting unit 120 and a flatsurface provided between the reflection surfaces. The prism structures102 and 104 are arranged in the form of a lattice between the lightemitting units 120 in such a manner that the longitudinal directions ofthe prism structures 102 and 104 correspond to the X direction and Ydirection, respectively. The angle converting unit 110 has an outputsurface 110 a over an entire surface thereof on the side opposite to thesubstrate 112. The output surface 110 a is in a plane that issubstantially parallel to the standard plane. One unit of the organic ELelement includes one light emitting unit 120 and a portion of the angleconverting unit 110, which portion corresponds to the light emittingunit 120. The display device 100 includes a plurality of the organic ELelements arranged corresponding to pixels. In FIG. 1, a perspective viewof a portion having arranged therein four organic EL elements in the Xdirection and three organic EL elements in the Y direction is shown as amain portion of the display device 100.

More particularly, the light emitting unit 120 has two opposingelectrode layers and a functional layer provided between the electrodelayers. When voltage is applied to between the two electrode layersusing an external power source, the functional layer of the lightemitting unit 120 supplies light. One of the electrodes in each lightemitting unit 120 is connected to a TFT circuit (not shown) that isprovided for each organic EL element. The display device 100 displays animage by a so-called active matrix method in which each organic ELelement is driven when electrical access is made to each TFT circuitthrough various interconnections.

The light emitting unit 120 supplies light to the side where the angleconverting unit 110 is provided. Light supplied from the light emittingunit 120 in a direction nearly perpendicular to the standard plane isemitted from the output surface of the angle converting unit 110directly. Light supplied from the light emitting unit 120 obliquelyreflects from the reflection surfaces of the prism structures 102 and104 and then emitted from the output surface of the angle convertingunit 110. The angle converting unit 110 reflects light that is suppliedfrom the light emitting unit 120 and enters the reflection surface inthe direction of the output surface to change the angle of the light.The angle of the light that travels obliquely from the light emittingunit 120 is changed in such a manner that an incident angle of the lightwith respect to the output surface is equal to or smaller than thecritical angle. The angle converting unit 110 changes the angle of thelight from the light emitting unit 120 to thereby reduce totalreflection on the output surface. With the angle converting unit 110,the display device 100 allows light from the light emitting unit 120 tobe taken out to the outside efficiently.

FIG. 2 is a cross-section of a main part of the display device 100. Theprism structures 102 are arranged in parallel in the X direction. Eachprism structure 102 has two reflection surfaces 205 provided on the sideof the light emitting unit 120 and a flat surface 203 provided betweenthe two reflection surfaces 205. One reflection surface 205 a is aninclined plane that is substantially flat. The reflection surface 205 aforms an angle θa with respect to the surface of the substrate 112,i.e., a plane that is parallel to the standard plane SS. Anotherreflection surface 205 b is also an inclined plane that is substantiallyflat. The reflection surface 205 b forms an angle θa′ with the surfaceof the substrate 112. The angle θa′ is substantially equal to (180°-θa).The reflection surfaces 205 a and 205 b on the both sides of the lightemitting unit 120 are arranged inclined in such a manner that the spacebetween the reflection surfaces 205 a and 205 b on the both sides of onelight emitting unit 120 widen toward the output surface. The flatsurfaces 203 are arranged facing to the output surface 207. The prismstructures 102 have a cross-section of an isosceles trapezoid with theflat surface 203 being the upper base. The angle converting unit 110 isconfigured in such a manner that an intersection M between a tangentline of the reflection surface 205 and a tangent line of the flatsurface 203 is at a predetermined distance between the standard plane SSand the output surface 207. The distance between the output surface andthe extremity of the reflection surfaces on the side of the outputsurface is predetermined. In other words, assuming a distance betweenthe intersection M and the output surface 207 to be “t”, the angleconverting unit 110 is configured in such a manner that t is a valuewithin a predetermined range. The height, h, of the prism structures 102and 104 is defined to a distance between the intersection M and thesurface of the substrate on which the prisms are arranged. In FIG. 2,the flat plane 203 of each angle converting unit 110 is depicted in anenlarged scale to some extent as compared with that shown in FIG. 1 toexplain that the flat surface 203 is provided.

For comparison, an organic EL element of which the distance t is notcontrolled is explained. Since it is usually difficult to form prismstructures 102 and 104 separately as individual components, the prismstructures 102 and 104 are formed by embossing one of a pair of platesto form a contour of each prism structure and filling and sealing aspace between the plates arranged in parallel with a sealant. Thickparallel plates are used as materials for preparing the angle convertingunits to avoid deformation or breakage of the plate upon the embossing.FIG. 3 is a diagram of an example of a display device 300 with an angleconverting unit 310 that includes a pair of thick parallel plates. Theangle converting unit 310 is configured in such a manner that assumingthe distance between the intersection M and the output surface 207 to bet′ and the height of the prism structures to be h′, the distance t′ isabout 5 times the height h′.

A portion of light that travels obliquely from the light emitting unit120 is not incident to the reflection surface and reaches to an outputsurface 307 of the angle converting unit 300. The light that is incidentto the output surface 307 of the angle converting unit 310 at an anglegreater than a critical angle totally reflects from the output surfaceand travels toward a point far from the light emitting unit 120 of theoriginal pixel from which the light was emitted. Some of the light thatreflected from the output surface 307 is incident to the light emittingunits 120 of the other pixels or to the reflection surfaces of the prismstructures and reflects from electrodes of the light emitting units 120and the reflection surfaces of the prism structures and then emittedthrough the output surface 307 out of the angle converting unit 310. Insome cases, crosstalk may occur in the display device 300 due to thelight L′ emitted from the pixels other than the original pixel. Thecrosstalk may cause deterioration of image quality, such as blurring ofthe contour of the image and appearance of ghost images that should nothave been displayed. The greater the distance t′, the more the amount ofthe light generated in the light emitting unit 120 of the original pixeland emitted from the pixel remote from the original pixel increases.Accordingly, the greater the distance 5′, the more the contour of theimage is blurred and the more the ghost image increases.

Referring back to FIG. 2, the organic EL element f the present inventionin the display device 100 is configured so as to satisfy inequality (1)0≦t<p(p−d−f)(tan θa)/(p+d−f)  (1)where t is a distance between the intersection M and the output surface207, p is a pitch at which light emitting units 120 are arranged in thepredetermined direction, which is the X direction, p being identical tothe distance between respective centers of adjacent light emitting units120, d is a length of the light emitting unit 120 in the predetermineddirection, which is the X direction, f is a length of the flat surface203 in the predetermined direction, which is the X direction; and θa isan angle between the reflection surface 205 and the standard plane SS.The angle converting unit 110 has a thickness that is equal to the sumof the height, h, of the prism structures 102 and the distance t.

The light incident to the output surface 207 at an angle equal to orsmaller than the critical angle is emitted through the output surface207 to the outside. On the other hand, the light incident to the outputsurface at an angle greater than the critical angle totally reflectsfrom the output surface 207 and travels toward the light emitting unit120 of the other pixel. The light L forms the smallest angle β withrespect to the standard plane SS. With the organic EL element configuredto satisfy the inequality (1) above, even when the light L with an angleβ with respect to the standard plane SS totally reflects from the outputsurface 207, the reflected light is incident to the reflection surface205 of a pixel after the next pixel from the original pixel from whichthe light was generated. In this manner, the display device 100 providedwith the organic EL element satisfying the inequality (1) allows thelight generated in a pixel to be emitted through the output surface 207within the range of the adjacent one pixel even when the light from thelight emitting unit 120 reflects totally from the output surface 207.

The organic EL element of the display device 100 may be configured tosatisfy the inequality (2)0≦t<p(p−d−f)(tan θa)/2(p+d−f)  (2)where t, p, d, d f, and θa have the same meanings as defined above. Withthe organic EL element that satisfies the inequality (2), the light Lhaving an angle β with respect to the substrate is incident to thereflection surface 205 of a pixel after the next pixel in the directionin which the light travels even when the light L is totally reflectedfrom the output surface 207. Therefore, with the organic EL element thatsatisfies the inequality (2) allows the light totally reflected from theoutput surface 207 to be emitted at a position adjacent to the originalpixel 220 from which the light is generated in the X direction. With thedisplay device 100 provided with the organic EL element that satisfiesthe inequality (2), the light from the light generating unit 120 can beemitted through the output surface 207 in the range corresponding to thepixel after the next pixel in the X direction. When the display device100 is configured in such a manner that t=0, the entire light generatedby the light emitting unit 120 can be emitted through the light outputsurface 207 within the range of the original pixel that includes thelight emitting unit 120 that generated the light. Therefore, the organicEL element that causes no crosstalk can be obtained.

When a pixel for red (R) light (hereafter, also referred to as “pixelR”), a pixel for green (G) light (hereafter, also referred to as “pixelG”), and a pixel for blue (B) light (hereafter, also referred to as“pixel B”) are arranged side by side in the X direction as shown in FIG.4, each pixel for a full color image in the display device 100 includesthe three pixels 220, i.e., the pixel R, the pixel G, and the pixel B.The observer can seldom recognize blurring of the images or appearanceof ghost images when the position of the emission of light is shifted bytwo pixels or so in the X direction due to crosstalk.

The configuration in the Y direction of the angle converting unit 110 ofthe organic EL element may be the same as that in the X direction. Inthe Y direction, parameters p, d, and f in the inequality (1) are set tothe pitch or lengths in the predetermined direction, i.e., Y-direction.By configuring the organic EL element in such a manner that the organicEL element satisfies the inequality (1) also in the Y direction, theoccurrence of the crosstalk in the Y direction can be limited to aregion of two pixels or less. With the above configuration, the observerseldom recognizes the occurrence of blurring of two pixels or so in theimage displayed in the display device 100. For this reason, the observercan seldom recognize blurring of the images or appearance of ghostimages when the position of the emission of light is shifted by twopixels or so in the Y direction due to crosstalk. The organic EL elementof the display device 100 configured to satisfy the inequality (1) canlimit the occurrence of the crosstalk to adjacent two pixels or less tominimize a reduction in image quality. This provides an effect that thedeterioration of the image quality can be reduced when light isefficiently emitted from the light emitting units 120. By satisfying theinequality (2) above, the organic EL element of the display device 100can further reduce the deterioration of the image quality.

Although the angle converting unit 110 of the display device isconfigured to have substantially planar reflection surfaces 205, theangle converting unit 110 may have curved reflection surfaces. Inaddition, the prism structures 102 and 104 in the angle converting unit110 may be configured to have no flat surfaces between the reflectionsurfaces 205 a and 205 b of each prism structure. When no flat surfaceis present between the reflection surfaces 205 a and 205 b of each prismstructure, the organic EL element may be configured to satisfy theinequality (4)0≦t<p(p−d)(tan θa)/(p+d)  (4)where t, p, d and θa have the same meanings as defined above.

Furthermore, the organic EL element may be configured to satisfy theinequality (5)0≦t<p(p−d)(tan θa)/2(p+d)  (5)where t, p, d and θa have the same meanings as defined above.

The organic EL element of the display device 100 is provided with prismstructures 102 and 104 each having reflection surface 205 in thedirections X and Y, which are two directions that cross at substantiallyright angles to each other in the standard plane SS. The organic ELelement is not limited to one that is provided with both a reflectionsurface 205 having a longitudinal axis in the X direction and areflection surface 205 having a longitudinal axis in the Y direction. Itis satisfactory that the reflection surface 205 of the organic ELelement has a longitudinal axis in one of the two directions that are atsubstantially right angles to each other. If the organic EL element isprovided with reflection surfaces 205 that are oblong in at least one ofthe two directions that cross at substantially right angels to eachother, the crosstalk can be reduced to a predetermined value or less. Asa result, the deterioration of the image quality can be decreased whenlight is efficiently emitted from the light generating unit 120.

FIGS. 5A and 5B are schematics for explaining a method of manufacturinga display element according to a second embodiment of the presentinvention. The organic EL element in the display device 100 in the firstembodiment above can be produced by the production method according tothe second embodiment. First, in a step a, which is a temporary bondingstep, a holding substrate 501 is temporarily bonded to a parallel plate510 made of a transparent resin. The holding substrate 501 is atransparent plate having a predetermined thickness, m, with whichbreakage of the parallel plate 510 can be sufficiently prevented in asubsequent pattern transferring step described below. The temporaryadhesion of the parallel plate 510 and the holding substrate 501 isperformed through a temporary adhesion layer 502.

In a step b, which is a pattern transferring step, a mold 503 is pressedonto the parallel plate 510 on the side opposite to the side where theholding substrate 501 is temporarily bonded in the temporary bondingstep. The pattern of the mold 503 is transferred to the parallel plate510 by thermoforming, for example, a vacuum forming method or apneumatic molding method. In a step c, the mold 503 is removed. As aresult, the reflection surface 205 is formed at a predetermineddistance, t, from the surface on which the holding substance 501 istemporarily bonded. The angle converting unit 110 is formed byprocessing the parallel plate 510 in the steps b and c.

In a step d, which is a laminating step, the surface of the angleconverting unit 110, which is a parallel plate, that is formed of thereflection surfaces 205 in the step b and the substrate 112 that ispreviously provided with the light emitting units 120 are laminated witheach other. The lamination of the angle converting unit 110 with thesubstrate 112 is performed with registration in position in such amanner that the light emitting unit 120 is arranged between adjacent twoprism structures, or between two opposing reflection surfaces 205. As aresult, the reflection surfaces 205, flat surfaces 203, and the surfaceof the substrate 112 define the form of the prism structures 102 and104.

The reflection surfaces 205 can be formed by, for example, forming ametal thin film. The materials of the metal thin film that can be usedinclude, for example, aluminum and silver. The metal thin film can beformed by vapor depositing or patterning a metal material on the surfaceof the angle converting unit 110 on the side of the substrate 112 beforethe angle converting unit 110 and the substrate 112 are laminated. Whenthe reflection surfaces 205 are formed by the forming of a metal thinfilm, the prism structures 102 and 104 can be formed by filling anadhesive in the cavities formed in the angle converting unit 110 afterthe step c.

When no flat surfaces 203 are provided between the opposing reflectionsurfaces 205, the tips of the prism structures 102 and 104 may have aninsufficient strength. The flat surfaces 203 are provided to ensure thestrength of he tips of the prism structures 102 and 104. When thestrength of the tips of the prism structures 102 and 104 is sufficientto prevent breakage of the prism structures 102 and 104, the prismstructures 102 and 104 need not have the flat surfaces 203. The contoursof the prism structures 102 and 104 may be defined by reflectionsurfaces 205 only. To provide the reflection surfaces 205 and the outputsurface 207 with a sufficiently small distance t from each other, it isdesirable that the flat surfaces 203 be configured to have as small aspossible an area so far as the breakage of the prism structures 102 and104 can be prevented.

The reflection surfaces 205 may be total reflection surfaces. When thereflection surfaces 205 that are total reflection surfaces are provided,the prism structures 102 and 104 may be formed by filling an inert gassuch as nitrogen gas in the cavities defined by the total reflectionsurfaces. The reflection surfaces 205 can totally reflect incident lightby utilizing a difference in refractive index between the resin memberthat constitutes the angle converting unit 110 and the prism structures102 and 104.

In a step e, which is a peeling step, the holding substrate 501, whichis temporarily bonded to the parallel plate in the temporary bondingstep a, is peeled off. To make it easy to peel the holding substrate501, the temporary adhesion layer 502 is desirably made of an adhesivethat can be peeled off by irradiation of ultraviolet rays, with heat orwith water. By making the holding substrate 501 readily peelable fromthe angle converting unit 110, the breakage of the display device 100can reduce. In this manner, the display device 100 can be produced.

By the production method according to the present embodiment, use of thestrong holding substrate 501 can sufficiently prevent the parallel plate510 from being broken even when a pattern is transferred to the thinparallel plate 510 using the mold 503. Since a pattern can betransferred to the thin parallel plate 510, an organic EL element with ashort distance t between the reflection surface 205 and the emittingsurface 207 can be readily produced. This enables production of organicEL elements that can reduce the occurrence of crosstalk. The breakage ofthe parallel plate during the production process can reduce.

FIG. 6 is a perspective view of a main part of a display device 600 thatincludes the display element according to a third embodiment of thepresent invention. The same or similar parts are designated by the samereference numerals as used in the first embodiment and overlappingexplanations are omitted. The display device 600 is an organic ELdisplay including an organic EL element that is the display element ofthe present invention. The display device 600 includes the substrate 112and an angle converting unit 610 laminated on the substrate 112. Theangle converting unit 110 is a parallel plate made of a transparentmember that has a refractive index of n. The angle converting unit 610has prism structures 602 and 604 on the surface on the side of thesubstrate 112.

FIG. 7 is a top plan view of a main part of the display device 600. Thetop plan configuration shows a state in which the prism structures 602that are oblong in the X direction and the prism structures 604 that areoblong in the Y direction cross at substantially right angles to eachother. The prism structures 602 and 604 are arranged between the lightemitting units 120. The prism structures 602 have reflection surfacesthat are oblong in a first direction, which is the X direction. Theprism structures 604 have reflection surfaces that are oblong in asecond direction, which the Y direction. The prism structures 602 and604 are defined by a reflection surface of an organic EL element and areflection surface of an organic EL element adjacent thereto, whichreflection surfaces abut each other. The angle converting unit 610includes reflection surfaces that are oblong in the X direction andreflection surfaces that are oblong in the Y direction.

Referring back to FIG. 6, the angle converting unit 610 has an outputsurface over the entire surface opposite to the side of the substrate112. The output surface is a plane substantially parallel to thestandard plane SS. A single unit of the organic EL element includes onelight emitting unit 120 and a part of the angle converting unit 610which part corresponds to the light emitting unit 120. The displaydevice 600 includes a plurality of organic EL elements that are arrangedcorresponding to pixels. FIG. 6 is a perspective view of a main part ofthe display device 600 in which four organic EL elements in the Xdirection and three organic EL elements in the Y direction arranged inthe form of a matrix.

The light emitting unit 120 generates light and supplies the light onthe side where the angle converting unit 610 is provided. The light fromthe light emitting unit 120 in the direction nearly perpendicular to thestandard plane is directly emitted to the outside through the emittingsurface of the angle converting unit 610. On the other hand, the lightfrom the light emitting unit 120 obliquely reflects from the reflectionsurfaces of the prism structures 602 and 604 and then emitted throughthe output surface of the angle converting unit 610. The angleconverting unit 610 reflects the light that is incident to thereflection surface from the light generating toward the output surfaceto change the angle of the light with respect to the standard plane. Theangle of the light from the light emitting unit 120 that travelsobliquely with respect to the standard plane is changed in such a mannerthat the angle of incidence of the light with respect to the outputsurface is equal to or below the critical angle. The angle convertingunit 610 reduces total reflection from the output surface by changingthe angle of the light from the light emitting unit 120. The displaydevice 600 provided with the angle converting unit 610 enables one totake out the light from the light emitting unit 120 to the outsideefficiently.

FIG. 8 is a cross-section of a main part of the display device 600. Theprism structures 604 are arranged parallel in the Y direction and at apredetermined pitch in the X direction. The light emitting units 120 areprovided on the standard plane SS. Each light emitting unit 120 has alow reflection electrode 721 on the standard plane SS. The lowreflection electrode 721 is a low reflection portion made of a memberhaving a predetermined reflection ratio or less of the incident light.The low reflection electrode 721 can be formed, for example, bylaminating titanium on indium tin oxide (hereafter, also referred to as“ITO” for short). Each of the prism structures 602 has two reflectionsurfaces 705 provided on the side of the light emitting unit 120. Thereflection surfaces 705 are substantially planar, inclined surfaceshaving an angle θb with respect to a plane that is parallel to thestandard plane SS on which the light emitting units 120 are provided.The reflection surfaces 705 are provided inclined in such a manner thatthe space defined between the reflection surfaces widen from the lightemitting unit 120 toward an output surface 707. The reflection surfaces705 are provided on the periphery of each light emitting unit 120.

The reflecting surfaces 705 can be formed by, for example, forming ametal thin film. The materials of the metal thin film that can be usedinclude, for example, aluminum and silver. The metal thin film can beformed by vapor depositing or patterning a metal material on the surfaceof the angle converting unit 610 on the side of the substrate 112 beforethe angle converting unit 610 and the substrate 112 are laminated. Whenthe reflection surfaces 705 are formed by the forming of a metal thinfilm, the prism structures 602 and 604 can be formed by filling anadhesive in the cavities formed in the angle converting unit 610.

FIG. 9 is a schematic for explaining how external light that enters thedisplay device 606 through the output surface 707 travels. The displaydevice 600 may cause a reduction in contrast because of illuminationlight in the room or external light such as sunlight that travels towardthe observer in the same manner as the light from the light emittingunit 120. In the organic EL element of the present invention, the lowreflection electrode 721 provided therein can reduce the reflection ofthe external light, which travels from the emission side to the lightemitting unit 120, toward the observer.

The organic EL element of the present invention in the display device600 is configured to satisfy the inequality (3){a sin(1/n)}/2+π/4<θb<π/2  (3)where θb is an angle (radian) between the reflection surface 705 and thestandard plane SS; and n is a refractive index of the material thatconstitutes the angle converting unit 610. The angle θb is shown as anangle between the reflection surface 705 and a plane that is parallel tothe standard plane SS. For example, assuming the refractive index n ofthe angle converting unit 610 to be 1.5 (n=1.5), the reflection surface705 can be provided at the angle θb that is greater than 65.90 andsmaller than 90° with respect to the standard plane SS (65.9<θb<90)according to the inequality (3).

The organic EL element of the display device 600 with the reflectionsurfaces 705 the angle of which with respect to the standard plane SS islimited to the range as defined by the inequality (3) does not allow theexternal light L1 that is incident to the reflection surface 705 fromthe output surface side 707 to be reflected toward the side of theoutput surface 707 and instead allows the external light L1 to travel inthe direction of the light emitting unit 120. The external light L1 thattravels in the direction toward the light emitting unit 120 is incidentto the low reflection electrode 721, so that the travel of the externallight L1 toward the output surface can be reduced. External light L2that is incident to the display device 600 at an angle of incidencegreater than that of the external light L1 is incident to the reflectionsurface 705 a and then incident to the reflection surface 705 b that isopposite to the reflection surface 705 a. The external light L2 that isincident to the reflection surfaces 705 a and 705 b downward isattenuated while the reflection is repeated between the reflectionsurfaces 705 a and 705 b.

Some of the light that travels from the reflection surface 705 a to theopposite reflection surface 705 b may travel toward the emission side.The light that reflects twice, that is, reflects from the reflectionsurfaces 705 a and 705 b totally reflects from the output surface 707 totravel toward the side of the light emitting unit 120 again. The twicereflected light can be attenuated by reflecting the light from, forexample, the reflecting surface 705.

FIG. 10 is a schematic for explaining how external light L3 isrepeatedly reflected between the reflection surface 705 of the prismstructure 602 and the reflection surface 705 of the prism structure 604.The organic EL elements of the display device 600 can reduce the amountof the external light not only by reflecting the external light L3between the reflection surfaces 705 (705 a and 705 b) but also byreflecting the external light L3 between the adjacent reflectingsurfaces 705 (the reflection surface 705 of the prism structure 602 andthe reflection surface 705 of the prism structure 604). The externallight L3, which travels rotating around the light emitting unit 120reflected by the reflection surfaces, is attenuated while the reflectionis repeated. An increasing number of times of reflection results in anincreasing degree of reduction in the amount of the light.

Accordingly, the organic EL elements of the display device 600 canprevent the external light that is incident to the reflection surface705 from the emission side from being emitted toward the side of theobserver after reflected from the reflection surface 705 once or twice.The amount of the external light that reflects from the reflectionsurfaces 705 three times or more can be reduced by repeating thereflection. The amount of the external light that is incident to thelight emitting unit 120 from the emission side and then travels towardthe emission side can be reduced by providing the low reflectionelectrode 721. This can minimizes a reduction in contrast when light isefficiently output from the light emitting unit 120.

The organic EL element of the present invention can reduce a decrease incontrast of images particularly under a light room environment. Theorganic EL element may be provided with an optical film on the outputsurface 707 of the angle converting unit 610 to prevent reflection. Forexample, the decrease in contrast can be further reduced by providing anoptical film that can prevent the reflection of the external light fromthe output surface 707 and allows the light from the light emitting unit120 to transmit through the output surface 707 to the outside.

FIG. 11 is a schematic of a display element according to a variation ofthe third embodiment of the present invention. An organic EL element ofa display device 1100 is provided no prism structures that are oblong inthe X direction, one of two directions that cross each other atsubstantially right angles on the standard plane SS. The organic ELelement is provided with only prism structures 1104 that are oblong inthe Y direction, the other of the above-mentioned two directions. Theorganic EL element according to the present variation has reflectionsurfaces that are oblong in the Y direction. The organic EL element ofthe display device 1100 can reduce a decrease in contrast by providingtherewith the reflection surfaces having the angle θb that satisfies theinequality (3) only in one of the two directions that are atsubstantially right angles to each other. Which of the two directionsthat cross at substantially right angles to each other to be alongitudinal direction of the reflection surfaces can be determinedappropriately depending on a main direction of incidence of the externallight that enters the display device 1100.

FIG. 12 is a cross-section of a main part of a display device 1200 witha display element according to a fourth embodiment of the presentinvention. The organic EL element, which is a display element of thepresent invention, is featured by having a light absorbing portion 1207.The same parts as that in the display element according to the thirdembodiment are designated by the same reference numerals and overlappingexplanation is omitted. Prism structures 1204 are oblong in the Ydirection. The contour of each prism structure 1204 is defined by thereflection surface 705 a of one organic EL element and the reflectionsurface 705 b of an organic EL element adjacent thereto, whichreflection surfaces abut each other at a position on the emission side.Each prism structure 1204 has an edge at the position where the tworeflection surfaces 705 a and 705 b abut each other. The light absorbingportion 1207 is provided on the edge of the prism structure 1204. Thelight absorbing portion 1207 is provided in the tip of the prismstructure 1204, which is in the form of an isosceles triangle.

The light absorbing portion 1207 can be made of a material that absorbsvisible light, such as black resin. External light L4 that is incidentto the light absorbing portion 1207 from the emission side is absorbedby the light absorbing portion 1207. By providing the light absorbingportion 1207, the light that is incident to the edge of the prismstructure 1204 is prevented from being reflected toward the emissionside. This reduces the external light that reflects and travels towardthe emission side, thereby reducing a decrease in contrast. Since thelight absorbing portion 1207 is provided on the edge where thereflection surfaces 705 abut each other, absorption of the display lightby the light absorbing portion 1207 can decrease. This makes it possibleto configure the organic EL element to absorb only the external light,so that the decrease in contrast can reduce.

To further reduce the absorption of the display light in the lightabsorbing portion 1207, it is desirable that the light absorbing portion1207 be designed to have a length as small as possible in the directionin which the display light is emitted, that is, the Z direction. Bydesigning the length in the Z direction as small as possible, the lightfrom the light emitting unit 1207 can be prevented from being incidentto the light absorbing portion 1207 to further decrease absorption ofthe display light by the light absorbing portion 1207. The lightabsorbing portion 1207 may be provided not only to the prism structures1204 that are oblong in the Y direction but also to the prism structures1204 that are oblong in the X direction.

FIG. 13 is a cross-section of a main part of a display device 1300 witha display element according to a fifth embodiment of the presentinvention. The organic EL element, which is a display element of thepresent invention is featured by having a polarizing plate 1301. Theparts the same as those in the display device 600 are designated by thesame reference numerals and overlapping explanation is omitted. A λ/4phase plate 1302 is provided on an output surface 1707 of the angleconverting unit 1610. The polarizing plate 1301 is provided on an outputsurface of the λ/4 phase plate 1302. The polarizing plate 1301 transmitsonly polarized light that vibrates in a specified direction, forexample, p-polarized light.

When external light enters the display device 1300 from the emissionside, the polarizing plate 1301 transmits only p-polarized lightcomponent out of the external light. The p-polarized light componentthat transmitted the polarizing plate 1301 is converted from linearlypolarized light to circularly polarized light through the λ/4 phaseplate 1302. The circularly polarized light reflects from the reflectionsurface 705 or a reflection electrode in a light emitting unit 1320 tobe incident to the λ/4 phase plate 1302. The light component thatremains circularly polarized in the light that is incident to the λ/4phase plate 1302 is then converted to s-polarized light. The lightconverted to s-polarized light and emitted from the λ/4 phase plate 1302is blocked by the polarizing plate 1301. The display device 1300provided with the polarizing plate 1301 can minimize the returning ofthe external light to the emission side.

The phase of the linearly polarized light is changed to λ/2 when thelinearly polarized light transmits through the λ/4 phase plate 1302twice. Utilizing this phenomenon, the polarized light that hastransmitted through the polarizing plate 1301 and vibrates in a specificoscillation direction can be converted to a polarized light thatvibrates in a direction other than the specific oscillation directionbefore the light enters the polarizing plate 1301 again. The circularlypolarized light that travels through the angle converting unit 1610 maycause a change in phase due to reflection from the reflection electrodeor reflection surface 705. The light of which the phase has changed byabout π/2 due to the reflection from the reflection electrode orreflection surface 705 is considered to enter the polarizing plate 1301as a polarized light that vibrates in a specific oscillation direction.The polarized light that vibrates in the specific oscillation directioncan cause a reduction in contrast when the light transmits thepolarizing plate 1301 and returns to the emission side.

When the reflection surfaces 705 are formed with a metal thin film, thephase of the light that reflects from the reflection surfaces 705changes depending on the angle of incidence. The display device 1300,like the display device 600 according to the third embodiment, isprovided with reflection surfaces 705 at a predetermined angle withrespect to the standard plane SS. The light that travels from thereflecting surface 705 a to the reflecting surface 705 b is totallyreflected from the output surface 1707 of an angle converting unit 1610to travel on the side of the light emitting unit 1320. The amount of thelight that reflects from the reflection surface 705 twice, i.e.,reflected from the reflection surfaces 705 a and 705 b and then travelson the side of the light emitting unit 1320 can be reduced by reflectingthe twice reflected light again from, for example, the reflectionsurface 705. From this it follows that the amount of the light thatreflects from the reflecting surface 705 twice and enters the polarizingplate 1301 can be reduced. As a result, the amount of the external lightthat transmits through the polarizing plate 1301 and returns to theemission side can be reduced, thereby reducing a decrease in contrast.

The organic EL element of the display device 1300 may include a lowreflection electrode in each light emitting unit 1320. With theconfiguration in which the low reflection electrode is provided in thelight emitting unit 1320, the light that is incident to the lightemitting unit 1320 directly or after being reflected from the reflectionsurface 705 can be prevented from traveling in the direction of thepolarizing plate 1301. This can reduce the amount of the external lightthat transmits through the polarizing plate 1301 and returns to theemission side.

The organic EL element of the display device 1300, like the thirdembodiment, includes the prism structures 602 and 604. The prismstructures 602 and 604 are provided on the substrate 112 in such amanner that the prism structures 602 and 604 have substantially the sameheight in the direction of a normal line to the standard plane SS, thatis, in the Z direction. The height, h, of the prism structures 602 and604 is a distance from the surface of the substrate 112 to an edge 1305of each prism structure.

How the light reflects from the edge 1305 of the prism structure 602 isexplained. FIG. 14 is a schematic for explaining how light reflects whenthe prism structures 604 are made higher than the prism structures 602as a comparison with the organic EL element according to the fifthembodiment. In some cases, external light L5 that reflects from the edge1305 of the prism structure 602 reflects on a reflection surface 1405 ofthe prism structure 604 that is adjacent to the prism structure 602 andtravels to the emission side. The light that reflects a plurality oftimes from the edge 1305, reflection surface 705 and the reflectionsurface 1405 and travels to the emission side has a considerable shiftin phase, so that the light may transmit through the polarizing plate1301.

FIG. 15 is a schematic for explaining how light reflects when the prismstructures 602 and the prism structures 604 having substantially thesame height are provided. When the prism structures 602 and 604 havesubstantially the same height, the external light L5 that reflects fromthe edge 1305 can be prevented from reflecting from the adjacentreflection surface 705. Since the external light L5 that reflects fromthe edge 1305 only has a less shift in phase, the external light L5 thatreflects on the edge 1305 is blocked by the polarizing plate 1301. Inthis manner, the external light that reflects from the edges 1305 of theprism structures 602 and 604 is prevented from traveling toward theemission side. This can reduce a decrease in contrast.

The display devices according to the above-mentioned embodiments includeorganic EL elements as display elements. However, the present inventionis not limited by use of the organic EL elements. For example, thedisplay element may be solid light emitting elements such as inorganicEL elements and light emitting diode (LED) elements. The display devicesthat include the display elements of the present invention can beapplied to display panels for electronic devices. The display panelsthat include the display elements of the present invention can be widelyapplied to various electronic devices such as mobile phones, personalcomputers, word processors, personal digital assistants (PDA), which aremobile type information technology (IT) devices, television, and carnavigators. The display elements of the present invention can be widelyapplied to illumination devices, electronic paper and so on.

Although the invention has been described with respect to a specificembodiment for a complete and clear disclosure, the appended claims arenot to be thus limited but are to be construed as embodying allmodifications and alternative constructions that may occur to oneskilled in the art that fairly fall within the basic teaching herein setforth.

1. A display element comprising: a light emitting unit that is provided on a standard plane, and supplies light; and an angle converting unit including a reflection surface that is provided on a periphery of the light emitting unit, and reflects the light from the light emitting unit; an output surface that outputs the light from the light emitting unit and the reflection surface; and a flat surface that is provided between the reflection surfaces in parallel with the output surface, wherein the angle converting unit converts an angle of the light by reflecting the light incident on the reflection surface from the light emitting unit toward the output surface, the light emitting unit is arranged in a matrix in two directions substantially perpendicular each other on the standard plane, and a geometrical shape of the angle converting unit satisfies following inequality 0≦t<p(p−d−f)(tan θa)/(p+d−f) where t is a distance between the flat surface and the output surface, p is a pitch at which the light emitting unit is arranged in a predetermined direction, d is a length of the light emitting unit in the predetermined direction, f is a length of the flat surface in the predetermined direction, and θa is an angle between the reflection surface and the standard plane.
 2. The display element according to claim 1, wherein the geometrical shape of the angle converting unit further satisfies following inequality 0≦t<p(p−d−f)(tan θa)/2(p+d−f).
 3. The display element according to claim 1, wherein the reflection surface has a longitudinal direction in at least one of the two directions substantially perpendicular each other on the standard plane.
 4. A method of manufacturing a display element that includes a light emitting unit that is provided on a standard plane, and supplies light; and an angle converting unit including a reflection surface that is provided on a periphery of the light emitting unit, and reflects the light from the light emitting unit, an output surface that outputs the light from the light emitting unit and the reflection surface, and a flat surface that is provided between the reflection surfaces in parallel with the output surface, the method comprising: bonding temporarily a holding substrate to a surface of a parallel plate; forming the reflection surface at a predetermined distance from a surface on which the holding substrate is temporarily bonded by pressing a mold having the predetermined pattern to other surface of the parallel plate opposite to the surface on which the holding substrate is temporarily bonded; bonding the surface of the parallel plate on which the reflection surface is formed and a substrate on which the light emitting unit is arranged in advance; and peeling the holding substrate temporarily bonded from the parallel plate.
 5. A display element comprising: a light emitting unit that is provided on a standard plane, and supplies light; and an angle converting unit that includes a reflection surface provided on a periphery of the light emitting unit, and converts an angle of the light by reflecting the light incident on the reflection surface from the light emitting unit toward an output surface, wherein a geometrical shape of the angle converting unit satisfies following inequality {a sin(1/n)}/2+π/4<θb<π/2 where θb is an angle in radian between the reflecting surface and the standard plane, and n is refractive index of a material of which the angle converting unit is made.
 6. The display element according to claim 5, wherein the light emitting unit is arranged in a matrix in two directions substantially perpendicular each other on the standard plane, and the reflection surface has a longitudinal direction in at least one of the two directions.
 7. The display element according to claim 5, wherein the light emitting unit is arranged in a matrix in two directions substantially perpendicular each other on the standard plane, and the angle converting unit includes a first reflection surface having a longitudinal direction in a first direction from among the two directions; and a second reflection surface having a longitudinal direction in a second direction from among the two directions.
 8. The display device according to claim 5, wherein the light emitting unit includes a low reflection portion at which a reflectivity of light incident to the light emitting unit from the output surface is equal to or less than a predetermined value.
 9. The display device according to claim 5, further comprising a polarizing plate that transmits only a polarized light in a specific oscillation direction on the output surface of the angle converting unit.
 10. The display device according to claim 7, wherein a structure formed with the first reflection surface and a structure formed with the second reflection surface have substantially same height in a direction normal to the standard plane.
 11. The display device according to claim 5, wherein the angle converting unit further includes a light absorbing portion that absorbs light at a position on the reflection surface on a side of the output surface. 